This invention relates to a novel process for the hydroformylation of certain unsaturated compounds. More specifically, it relates to the use of certain iron carbonyl catalysts.
The hydroformylation of olefins with hydrogen and carbon monoxide is a well-known process. Most known processes require the use of rhodium or cobalt in various forms as catalysts. These processes are generally run at elevated temperatures and pressures, for example, about 125.degree. C. to 175.degree. C. and about 3000 to 5000 psig. Cobalt- and rhodium-based catalysts are expensive and often render processes using them uneconomical. Furthermore, many of these catalysts require stringent conditions in order to be operable.
As a result of these problems many researchers have attempted to use other catalyst systems for hydroformylation of olefins. An olefin can be converted to the next higher alcohol by reaction with water and carbon monoxide in the presence of a catalyst comprising a Bronsted or Lewis base and iron pentacarbonyl under relatively mild temperatures and pressures. W. Reppe et al., Justus Liebigs Ann. Chem., 582 133 (1953). Kang et al., J. Am. Chem. Soc., 99 8323 (1977), disclose that the presence of a strong base is necessary for iron pentacarbonyl to be catalytic in he Reppe synthesis. In hydroformylation reactions, carbon dioxide is a by-product which reacts with the base to deactivate the catalytic system. Such side reactions result in significant reductions in the number of times the catalyst can be regenerated. As a result, these processes requre large amounts of base for the catalyst to continue its catalytic activity.
What is needed is a catalyst system for hydroformylation of olefins which does not contain expensive metals such as cobalt or rhodium and which requires mild reaction conditions. What is further needed is a process which retains its catalytic activity for extended periods of time without the use of large amounts of base.